CVE-2026-98851
Full vulnerability record from the local CVENow database.
Description
In the Linux kernel, the following vulnerability has been resolved: netfilter: nft_flow_offload: drop flowtable reference on init error path nft_flow_offload_init() bumps the flowtable use count with nft_use_inc() before calling nf_ct_netns_get(). When the latter fails, the error is returned as-is and the reference is leaked. The upper layers do not balance it either: nf_tables_newexpr() clears expr->ops when the expression init callback fails, so the nft_expr_more() iteration in nft_rule_expr_deactivate() and nf_tables_rule_destroy() stops right before the failed expression and its ->destroy callback, which would drop the reference, never runs. Each failed rule addition therefore leaks one flowtable reference and the flowtable can no longer be removed: NFT_MSG_DELFLOWTABLE keeps reporting -EBUSY even though no rule references it. Save the nf_ct_netns_get() return value and undo the nft_use_inc() when it fails, restoring the inc/dec pairing within nft_flow_offload_init() itself.
Severity
Not scored
CVSS score
Not available
Vulnerability status
Received
Source identifier
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Published
2026-10-18 16:17:39.490000
Last modified
2026-10-30 13:21:30.727000
View original CVE JSON
{
"id": "CVE-2026-98851",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"published": "2026-10-18T16:17:39.490",
"lastModified": "2026-10-30T13:21:30.727",
"vulnStatus": "Received",
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nft_flow_offload: drop flowtable reference on init error path\n\nnft_flow_offload_init() bumps the flowtable use count with\nnft_use_inc() before calling nf_ct_netns_get(). When the latter\nfails, the error is returned as-is and the reference is leaked.\n\nThe upper layers do not balance it either: nf_tables_newexpr()\nclears expr->ops when the expression init callback fails, so the\nnft_expr_more() iteration in nft_rule_expr_deactivate() and\nnf_tables_rule_destroy() stops right before the failed expression\nand its ->destroy callback, which would drop the reference, never\nruns.\n\nEach failed rule addition therefore leaks one flowtable reference\nand the flowtable can no longer be removed: NFT_MSG_DELFLOWTABLE\nkeeps reporting -EBUSY even though no rule references it.\n\nSave the nf_ct_netns_get() return value and undo the nft_use_inc()\nwhen it fails, restoring the inc/dec pairing within\nnft_flow_offload_init() itself."
}
],
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"affectedData": [
{
"vendor": "Linux",
"product": "Linux",
"defaultStatus": "unaffected",
"programFiles": [
"net/netfilter/nft_flow_offload.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"versions": [
{
"version": "a3c90f7a2323b331ae816d5b0633e68148e25d04",
"lessThan": "4e5a6d89083af6f23f0ac2cb611ef267590a3ece",
"versionType": "git",
"status": "affected"
},
{
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"versionType": "git",
"status": "affected"
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},
{
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"product": "Linux",
"defaultStatus": "affected",
"programFiles": [
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],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"versions": [
{
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"status": "affected"
},
{
"version": "0",
"lessThan": "4.16",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "5.10.273",
"lessThanOrEqual": "5.10.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "5.15.224",
"lessThanOrEqual": "5.15.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.1.191",
"lessThanOrEqual": "6.1.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.6.160",
"lessThanOrEqual": "6.6.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.12.113",
"lessThanOrEqual": "6.12.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.18.56",
"lessThanOrEqual": "6.18.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "7.2.10",
"lessThanOrEqual": "7.2.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "7.3",
"lessThanOrEqual": "*",
"versionType": "original_commit_for_fix",
"status": "unaffected"
}
]
}
]
}
],
"metrics": {},
"references": [
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"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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{
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}